1. The Field of the Invention
The present invention is in the field of dental bleaching compositions, systems and methods for whitening a person's teeth. The invention relates to dental bleaching compositions that are dispensed and applied to tooth surfaces as a gel and then foam in situ on the tooth surfaces.
2. The Relevant Technology
To achieve whiter teeth, people often have their teeth covered with veneers or chemically bleached. A conventional dental professional bleaching process generally involves: (1) making an alginate impression of the patient's teeth; (2) making a stone cast or model of the impression; (3) vacuum forming a dental tray from the model, usually from a heated sheet of thin ethyl vinyl acetate (EVA) material; (4) trimming the upper tray rim to exclude gingival coverage; (5) introducing a bleaching gel into the tray; and (6) placing the tray over the teeth to be bleached for a suitable time period to effect tooth bleaching.
Because of the time and cost associated with forming customized trays, less time consuming and costly alternatives have been developed. Examples include boil and bite trays and non-custom trays, both of which tend to bulky and uncomfortable, flexible strips, which have a tendency to slip off the teeth, and paint-on bleaching compositions, which are directly exposed to saliva in a person's mouth.
Dental bleaching compositions are usually in the form of a liquid or gel. Liquid bleaching compositions do not provide adhesion to teeth and can run out of the tray used to apply the composition. Gel bleaching composition, particularly those which are sticky and viscous, are better able adhere to a person's teeth and can assist in holding a dental tray over the teeth during treatment. Maintaining good adhesion to a person's teeth is believed to provide superior bleaching by maintaining continuous contact between the bleaching composition and the person's teeth. In reality, the inventors discovered that dental bleaching gels, particularly those which are stiff and highly viscous, can become depleted of bleach at the contact interface with the tooth surfaces, requiring removal and reapplication of bleaching gel to complete the bleaching process. Finally, there are foamable bleaching compositions such as toothpastes that include a surfactant foaming agent that generates foam while brushing by mixing the toothpaste with saliva in the person's mouth.